Gate driver with serial communication

ABSTRACT

A gate driver includes a drive signal input terminal, a drive signal output terminal, a gate drive circuit, and a serial communication interface. The drive signal input terminal is configured to receive a gate drive signal. The gate drive circuit is coupled to the drive signal input terminal and the drive signal output terminal. The gate drive circuit is configured to provide the gate drive signal to the drive signal output terminal. The serial communication interface is coupled to the drive signal input terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

Under 35 U.S.C. §§ 119(e), 120, this continuation application claimsbenefits of and priority to U.S. patent application Ser. No. 16/388,353(TI-78422A), filed on Apr. 18, 2019, which claims priority to U.S.patent application Ser. No. 15/854,515 (TI-78422), filed on Dec. 26,2017, which claims priority to U.S. Provisional Patent Application No.62/510,066, filed May 23, 2017. The entirety of the above referencedapplications are hereby incorporated herein by reference.

BACKGROUND

In order to reduce switching losses in power transistors, the powertransistors are switched on and off very rapidly. Because the powertransistor's control terminal may present significant capacitance, agate driver circuit may be employed to buffer an input signal and drivethe power transistor's control terminal. The gate driver circuitreceives a low-power input signal and buffers the input signal toproduce a high-current signal that quickly charges or discharges theinput capacitance of the power transistor. Examples of power transistorswith which a gate driver circuit may be employed include insulated gatebipolar transistors and metal oxide semiconductorfield-effect-transistors.

SUMMARY

A gate driver that includes addressable serial communication isdisclosed herein. In one example, a gate driver includes a drive signalinput terminal, a drive signal output terminal, a gate drive circuit,and a serial communication interface. The drive signal input terminal isconfigured to receive a gate drive signal. The gate drive circuit iscoupled to the drive signal input terminal and the drive signal outputterminal. The gate drive circuit is configured to provide the gate drivesignal to the drive signal output terminal. The serial communicationinterface is coupled to the drive signal input terminal.

In another example, a motor drive circuit includes plurality of powertransistors and a plurality of gate drivers. The power transistors areconfigured to drive an electric motor. One of the gate drivers isconnected to a control terminal of each of the power transistors. Eachof the gate drivers includes a drive signal input terminal, a gate drivecircuit, and a serial communication interface. The gate drive circuit iscoupled to the drive signal input terminal. The gate drive circuit isconfigured to drive a signal received at the drive signal input terminalonto a control terminal of the one of the power transistors connected tothe gate driver. The serial communication interface is coupled to thegate drive circuit. The serial communication interface includes a datainput terminal and control circuitry. The control circuitry isconfigured to enter an address initialization mode during initializationof the gate driver, and to remain in the address initialization modeuntil the signal received at the drive signal input terminal isactivated and thereafter inactivated.

In a further example, a traction inverter includes a plurality of powertransistors, a plurality of gate drivers, and a controller. The powertransistors are configured to drive an electric motor. Each of the gatedrivers is connected to a control terminal of one of the powertransistors. The controller includes a plurality of motor driveterminals. Each of the motor drive terminals is connected to a drivesignal input terminal of one of the gate drivers. Each of the gatedrivers includes a serial communication interface coupled to thecontroller. The serial communication interface includes a data inputterminal, and control circuitry. The control circuitry is configured toenter an address initialization mode during initialization of the gatedriver, and to remain in the address initialization mode until thesignal received at the drive signal input terminal is activated andthereafter inactivated. While in the address initialization mode, thecontrol circuitry is configured to assign a value received via the datainput terminal to be an address of the serial communication interface.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of various examples, reference will now bemade to the accompanying drawings in which:

FIG. 1 shows a block diagram for power electronics of an electric orhybrid electric vehicle in accordance with various examples;

FIG. 2 shows a schematic diagram for a traction inverter in accordancewith various examples;

FIG. 3 shows a block diagram for a gate driver that includes anaddressable serial interface in accordance with various examples;

FIG. 4 shows a flow diagram for a method for operating a serialcommunication interface of a gate driver in accordance with variousexamples; and

FIG. 5 shows a timing diagram for address assignment in a serialcommunication interface of a gate driver in accordance with variousexamples.

DETAILED DESCRIPTION

Certain terms have been used throughout this description and claims torefer to particular system components. As one skilled in the art willappreciate, different parties may refer to a component by differentnames. This document does not intend to distinguish between componentsthat differ in name but not function. In this disclosure and claims, theterms “including” and “comprising” are used in an open-ended fashion,and thus should be interpreted to mean “including, but not limited to .. . .” Also, the term “couple” or “couples” is intended to mean eitheran indirect or direct wired or wireless connection. Thus, if a firstdevice couples to a second device, that connection may be through adirect connection or through an indirect connection via other devicesand connections. The recitation “based on” is intended to mean “based atleast in part on.” Therefore, if X is based on Y, X may be a function ofY and any number of other factors.

Power electronics, including power transistors, are used in a widevariety of applications. Electric vehicles and/or hybrid electricvehicles are applications that make significant use of high voltagepower electronics. For example, vehicle power electronics may include athree-phase rectifier, a boost converter, and a traction inverter. Thethree-phase rectifier converts alternating current (AC) power from apower main to direct current (DC) power to charge the vehicle's battery.The boost converter boosts the battery voltage. The traction inverterconverts the DC power provided by the boost converter and/or thevehicle's battery to AC power to generate rotating magnetic field in amotor that drives the vehicles wheels. Silicon or silicon carbide metaloxide semiconductor field effects transistors (MOSFETs) may be used forthe rectifier and/or boost converter. Insulated gate bipolar transistors(IGBTs) may be used in the traction inverter.

Each of the rectifier, boost converter, and traction inverter mayinclude a gate driver to drive each power transistor. Reliable operationof the gate driver ensures the torque safety of the electric powertrain. The gate drivers disclosed herein include a serial interface toenable communication between gate driver and a controller. The serialinterface may be used to implement monitoring, diagnosis, andconfiguration of the gate drivers.

Serial peripheral interface (SPI) is a type of serial communication thatmay be applied in gate drivers. SPI is a synchronous serialcommunication system. Each device implementing SPI includes a data inputterminal, a data output terminal, a clock terminal, and one or moreselect terminals. An SPI master device drives a clock signal onto itsclock terminal, drives output data onto its data output terminalsynchronous with the clock, and samples data on its data input terminalsynchronous with the clock. The SPI master activates a select signal ona select terminal to choose a slave for communication. An SPI slavedevice receiving the activated select signal on its select terminalreceives a clock signal on its clock terminal, drives output data ontoits data output terminal synchronous with the clock, and samples data onits data input terminal synchronous with the clock.

Devices communicating via SPI may be arranged in parallel ordaisy-chained configurations. In the parallel configuration, a separateselect signal is provided for each slave device while the data lines andclock signal are shared by all slave devices. The parallel configurationprovides high data throughput, but requires that the master deviceinclude a select terminal for each slave device, thus requiring a largenumber of terminals in some applications. For example, in an electricvehicle with a six-phase traction inverter, more than 15 selectterminals may be needed, which may not be readily available incommercial microcontroller units. In the daisy chain configuration, theselect signal and clock signal are shared by all slave devices while thedata lines are looped in series. The daisy chain configuration allowsfor a reduced number of terminals on the master device, but limitscommunication bandwidth to f_(BW)/N, where f_(BW) is the SPI clockfrequency and N is the number of slave devices.

In implementations of the present disclosure, a full duplex serialcommunication interface, such as SPI, is included in a gate drivercircuit. The serial communication interface includes an addressinitialization mode. While operating in the address initialization modethe serial communication interface applies a signal received at a drivesignal input terminal of the gate driver as a select signal to enablecapture of an address value. Any number of serial communicationinterfaces may be connected to a master device, with data inputterminals of all slave devices connected, data output terminals of allslave devices connected, clock terminals of all slave devices connected,and select terminals of all slave devices connected, thereby reducingthe number of terminals required on the master device. After assignmentof an address to the serial communication interface, the serialcommunication interface captures data received via its data inputterminal and transmits data via its data output terminal only if asignal at its select terminal is activated and the address assigned tothe serial communication interface has been received via the data inputterminal.

FIG. 1 shows a block diagram for power electronics 100 of an electricvehicle or hybrid-electric vehicle. The power electronics 100 include abattery charger 102, a battery 104, a boost converter 106, a tractioninverter 108, and a motor 110. The battery charger 102 receives AC powerfrom the power mains and converts the AC power to DC power 112 that isused to charge the battery 104. The AC power may be three-phase in someimplementations. The battery charger 102 includes rectificationcircuitry to convert the AC power to DC power. The rectificationcircuitry may include silicon or silicon carbide MOSFETs and controlcircuitry coupled to the MOSFETs to perform the rectification.

The battery 104 may include any number of rechargeable battery cells(e.g., lithium-ion battery cells) connected to provide an output voltagesuitable for driving the boost converter 106.

Output 114 of the battery 104 is provided to the boost converter 106.The boost converter 106 is a switch-mode DC-DC converter that boosts thebattery output 114 to a voltage suitable for driving the motor 110. Forexample, the output voltage 116 of the boost converter 106 may begreater than 100 volts. The boost converter 106 may include silicon orsilicon carbide MOSFETs as switches to enable generation of the boostedDC voltage.

The traction inverter 108 is a motor drive circuit that receives theoutput 116 of the boost converter 106 and generates AC signals 118 todrive the motor 110. In various implementations, the traction inverter108 can be a three-phase inverter, a six-phase inverter, and/or othermulti-phase inverters. The signals 118 generated by the tractioninverter 108 may cause the motor 110 to rotate the wheels of an electricor hybrid-electric vehicle.

FIG. 2 shows a schematic diagram for the traction inverter 108. Thetraction inverter 108 includes power transistors 202A, 202B, 202C, 202D,202E and 202F, a plurality of gate drivers (also referred to as “gatedrivers”) 204A, 204B, 204C, 204D, 204E and 204F, and a controller 210.The power transistors 202A, 202B, 202C, 202D, 202E and 202F may beidentical and the gate drivers 204A, 204B, 204C, 204D, 204E and 204F maybe identical. The high-side power transistors 202A, 202C, and 202E arecoupled to output 116 provided by the boost converter 106. The low-sidepower transistors 202B, 202D, and 202F are connected to ground or otherreference voltage. The power transistors 202A-202F may be insulated gatebipolar transistors (IGBTs). The power transistors 202A and 202B producea combined output to drive a first phase of the motor 110. The powertransistors 202C and 202D produce a combined output to drive a secondphase of the motor 110. The power transistors 202E and 202F produce acombined output to drive a third phase of the motor 110.

Each of the power transistors 202A-202F is connected to and driven byone of the gate drivers 204A-204F. More specifically, the gate driver204A drives the control terminal (the gate) of the power transistor202A, the gate driver 204B drives the control terminal of the powertransistor 202B, the gate driver 204C drives the control terminal of thepower transistor 202C, the gate driver 204D drives the control terminalof the power transistor 202D, the gate driver 204E drives the controlterminal of the power transistor 202E, and the gate driver 204F drivesthe control terminal of the power transistor 202F.

The gate drivers 204A-204F are coupled to the controller 210. Thecontroller 210 may be a microcontroller or other instruction executionmachine. The controller 210 includes a high-side pulse width modulator212, a low-side pulse width modulator 214, and a serial communicationinterface 216. The controller 210 may also include other components andsystems that have been omitted in the interest of clarity. For example,the controller 210 may include an instruction execution unit, memory forprogram and data storage, timing peripherals, communication peripherals,etc. The high-side pulse width modulator 212 is coupled to the high-sidepower transistors 202A, 202C, and 202E. The low-side pulse widthmodulator 214 is coupled to the low-side power transistors 202B, 202D,and 202F. Drive signals generated by the high-side pulse width modulator212 and the low-side pulse width modulator 214 are provided to the gatedrivers 204A-204F to be driven onto the control terminals of the powertransistors 202A-202F. The controller 210 includes a plurality of motordrive terminals 218 via which the outputs of the high-side pulse widthmodulator 212 and the low-side pulse width modulator 214 are provided tothe gate drivers 204A-204F.

The serial communication interface 216 may be an SPI master interface.The serial communication interface 216 generates a clock signal, anoutput data signal, and a select signal that are provided to the gatedrivers 204A-204F. The serial communication interface 216 receives aninput data signal from the gate drivers 204A-204F. The gate drivers204A-204F are connected in parallel with respect to the clock signal,the output data signal, the input data signal, and the select signal.

FIG. 3 shows a block diagram for a gate driver 300 that includes anaddressable serial interface in accordance with various examples. Thegate drivers 204A-204F may be implementations of the gate driver 300.The gate driver 300 includes a drive signal input terminal 302, a gatedrive circuit 304, a serial communication interface 306, a drive dataoutput terminal 312, a data input terminal 314, and a select terminal316. The gate drive circuit 304 receives as input a signal to be drivenonto the control terminal of a power transistor. For example, withrespect to the traction inverter 108, the gate drive circuit 304 mayreceive an output of the high-side pulse width modulator 212 to bedriven onto a control terminal of one of the power transistors202A-202F. The gate drive circuit 304 may include a level converterand/or amplifier to increase the voltage and/or current of the signaldriven onto the control terminal of the power transistor.

The serial communication interface 306 may be an SPI slave interface.The serial communication interface 306 includes control circuitry 308.The serial communication interface 306 may also include other componentsand systems that have been omitted in the interest of clarity. Forexample, the serial communication interface 306 may include a serialdata input register that converts received serial data to parallel form,and a serial data output register that converts parallel data to serialform for transmission. The serial communication interface 306 receivesthe clock signal generated by the controller 210, receives, via theselect terminal 316, the select signal generated by the controller 210,and receives, via the data input terminal 314, the input data signalgenerated by the controller 210. When connected as illustrated in FIG.2, the gate driver 300 provides improved bandwidth relative to adaisy-chained configuration, and allows for a lower number ininput/output terminals on the controller 210 relative to parallelconfigurations. The gate driver 300 provides these advantages byallowing an address value to be assigned to the serial communicationinterface 306. Accordingly, the control circuitry 308 includes anaddress register 310.

During initialization of the gate driver 300, the serial communicationinterface 306 enters an address initialization mode. While in theaddress initialization mode, in order to allow the controller 210 toselect each instance of the gate driver 300 for address assignment, thegate driver 300 applies the drive signal received via the drive signalinput terminal 302 as a select signal. When the drive signal receivedvia the drive signal input terminal 302 is activated, the serialcommunication interface 306 captures the address value received via thedata input terminal 314 and stores the address value in the addressregister 310. After the address has been assigned, the gate driver 300transitions from the address initialization mode to an operation mode.In the operation mode, the drive signal received via the drive signalinput terminal 302 is not applied to control the serial communicationinterface 306. Rather, the control circuitry 308 captures an addressvalue received via the data input terminal 314 to determine whether theserial communication interface 306 is to receive and transmit data, andthe drive signal received via the drive signal input terminal 302 isamplified and provided to a connected power transistor.

FIG. 4 shows a flow diagram for a method 400 for operating a serialcommunication interface of a gate driver in accordance with variousexamples. Though depicted sequentially as a matter of convenience, atleast some of the actions shown can be performed in a different orderand/or performed in parallel. Additionally, some implementations mayperform only some of the actions shown. In some implementations, atleast some of the operations of the method 400 can be implemented by thegate driver 300.

In step 402, the gate driver 300 is initializing. For example, power hasbeen applied to the gate driver 300, and the gate driver 300 is in apower up initialization state. The serial communication interface 306 isin address initialization mode. In address initialization mode, theserial communication interface 306 applies the drive signal received viathe drive signal input terminal 302 as a select signal to determinewhether the serial communication interface 306 is to apply a data valuereceived via the data input terminal 314 as an address. For example,control circuitry 308 may include logic circuits that, in the addressinitialization mode, enable receipt of an address value only if thedrive signal received via the drive signal input terminal 302 isactivated. If the drive signal received via the drive signal inputterminal 302 is activated, then the control circuitry 308 determinesthat the serial communication interface 306 is being selected to receivean address value. If the drive signal received via the drive signalinput terminal 302 is not activated, then the control circuitry 308continues to monitor for activation of the drive signal received via thedrive signal input terminal 302.

In step 404, responsive to the determination, in block 402, that thedrive signal received via the drive signal input terminal 302 isactivated, the serial communication interface 306 captures the datavalue received via the data input terminal 314 and stores the captureddata value in the address register 310. The drive signal received viathe drive signal input terminal 302 is inactivated (e.g., signal 218A isinactivated by the high-side pulse width modulator 212) whentransmission of the address value is complete.

In step 06, responsive to assignment of the address to the serialcommunication interface 306 in block 404, the serial communicationinterface 306 exits the address initialization mode and enters operationmode. In some implementations of the gate driver 300, the serialcommunication interface 306 may also receive of an instruction via thedata input terminal 314 (e.g., an enter operation mode instructiontransmitted using a broadcast address) to transition into operationmode.

In step 408, the gate driver 300 is in operation mode and the serialcommunication interface 306 is monitoring the data input terminal 314for receipt of an address. Activation of a signal at the select terminal316 (i.e. a select signal) indicates that data is being transferred.Accordingly, activation of the selection signal may activate circuitrythat enables the serial communication interface 306 to capture data bitspresent on the data input terminal 314 at edges of the clock signal 222.For example, a first N bits captured after activation of the selectsignal may specify an address. If an address is received, the serialcommunication interface 306 compares the received address to the addressvalue stored in the address register 310 to determine whethersubsequently received data is directed to the serial communicationinterface 306 and the serial communication interface 306 is to drive thedata output terminal 318. If the received address matches the addressstored in the address register 310, then in step 410, the serialcommunication interface 306 captures and applies data received via thedata input terminal 314 and transmits data to the controller 210 via thedata output terminal 318.

FIG. 5 shows a timing diagram for address assignment in a serialcommunication interface of a gate drivers 204A-204F in accordance withvarious examples. At 502, power is applied to the gate drivers 204A-204Fand the gate drivers 204A-204F enter address initialization mode. At504, the controller 210 activates the drive signal 218A and the selectsignal 220. While the drive signal 218A and the select signal 220 areactivated, the controller 210 drives the clock signal 222 and drives adata value onto the data input terminal of the gate driver 204A. Thegate driver 204A is monitoring the drive signal 218A and select signal220, and on recognition of the activation of the drive signal 218A andthe select signal 220, the gate driver 204A applies the clock signal 222to capture the data value on the data input terminal and assign thecaptured data value to be the address of the gate driver 204A. Whentransmission of the data value onto the data input terminal is complete,the controller 210 inactivates the drive signal 218A and the selectsignal 220 at 506. When the drive signal 218A and the select signal 220are inactivated the gate driver 204A may transition from addressinitialization mode to operation mode.

At 508, the controller 210 activates the drive signal 218B and theselect signal 220. While the 218B and the select signal 220 areactivated, the controller 210 drives the clock signal clock signal 222and drives a data value onto the data input terminal of the gate driver204C. The gate driver 204C is monitoring the 218B and select signal 220,and on recognition of the activation of the 218B and the select signal220, the gate driver 204C applies the clock signal 222 to capture thedata value on the data input terminal and assign the captured data valueto be the address of the gate driver 204C. When transmission of the datavalue onto the data input terminal is complete, the controller 210inactivates the 218B and the select signal 220 at 510. When the drivesignal 218B and the select signal 220 are inactivated the gate driver204C may transition from address initialization mode to operation mode.

At 512, the controller 210 activates the drive signal 218C and theselect signal 220. While the drive signal 218C and the select signal 220are activated, the controller 210 drives the clock signal clock signal222 and drives a data value onto the data input terminal of the 204E.The gate driver 204E is monitoring the drive signal 218C and selectsignal 220, and on recognition of the activation of the drive signal218B and the select signal 220, the gate driver 204E applies the clocksignal 222 to capture the data value on the data input terminal andassign the captured data value to be the address of the gate driver204E. When transmission of the data value onto the data input terminalis complete, the controller 210 inactivates the drive signal 218C andthe select signal 220 at 514. When the drive signal 218C and the selectsignal 220 are inactivated the gate driver 204E may transition fromaddress initialization mode to operation mode.

The controller 210 continues the process described above to assignaddress values to the gate drivers 204B, 204D, and 204F. On completionof address assignments, the controller 210 may broadcast an instructionin interval 516 that causes the gate drivers 204A-204F to transitionfrom the address initialization mode to the operation mode and/or toenable output to the power transistors 202A-202F.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present disclosure. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
 1. A device comprising: a transistor having a gate;an input terminal; a serial communication interface having a controlinput; and a drive circuit having a drive input and a drive output, thedrive output coupled to the gate; in which the input terminal is coupledthrough a first path to the drive input and through a second path to thecontrol input, and the second path diverges from the first path.
 2. Thedevice of claim 1, wherein the first path diverges from the second pathat the input terminal.
 3. The device of claim 1, wherein the first pathis independent of the second path.
 4. The device of claim 1, wherein thefirst path is external to the serial communication interface.
 5. Thedevice of claim 1, wherein the second path is external to the drivecircuit.
 6. The device of claim 1, wherein the input terminal isconfigured to receive a pulse width modulation (PWM) signal, the firstpath is configured to transmit the PWM signal from the input terminal tothe drive input and bypass the serial communication interface.
 7. Thedevice of claim 1, wherein the input terminal is configured to receive apulse width modulation (PWM) signal, the first path is configured totransmit the PWM signal from the input terminal to the control input andbypass the drive circuit.
 8. The device of claim 1, wherein the serialcommunication interface includes: a data input terminal configured toreceive data; and a control circuit configured to assign a value to anaddress register based on the data when the control circuit is initiatedby a signal from the input terminal.
 9. The device of claim 8, whereinthe signal has a pulse width, and the control circuit is in an addressinitialization mode for a duration of the pulse width.
 10. The device ofclaim 8, wherein the address register has a 1-to-1 correspondence withthe drive circuit.
 11. A traction inverter comprising: a transistorhaving a gate; an input terminal; a drive circuit having a drive inputcoupled to the input terminal, and a driver output coupled to the gate;and a serial communication interface having a control circuit configuredto assign a value to an address register responsive to a signal from theinput terminal.
 12. The traction inverter of claim 11, furthercomprising: a data input terminal configured to receive address data,wherein the control circuit is configured to assign the value to theaddress register based on the address data during an assertion period ofthe signal.
 13. The traction inverter of claim 11, wherein the signalhas a pulse width, and the control circuit is in an addressinitialization mode for a duration of the pulse width.
 14. The tractioninverter of claim 11, wherein the address register has a 1-to-1correspondence with the drive circuit.
 15. The traction inverter ofclaim 11, wherein: the input terminal is coupled through a first path tothe drive input and through a second path to the control circuit, andthe second path diverges from the first path.
 16. A system comprising:an input terminal; a silicon carbide transistor having a gate; a drivecircuit having a drive input coupled to the input terminal and a driveroutput coupled to the gate; and a serial communication interface havinga control circuit configured to assign a value to an address registerresponsive to a signal from the input terminal.
 17. The system of claim16, further comprising: a data input terminal configured to receiveaddress data, wherein the control circuit is configured to assign thevalue to the address register based on the address data during anassertion period of the signal.
 18. The system of claim 16, wherein thesignal has a pulse width, and the control circuit is in an addressinitialization mode for a duration of the pulse width.
 19. The system ofclaim 16, wherein the address register has a 1-to-1 correspondence withthe drive circuit.
 20. The system of claim 16, wherein: the inputterminal is coupled through a first path to the drive input and througha second path to the control circuit, and the second path diverges fromthe first path.